AbstractBackground and Objective: Attention deficit hyperactivity disorder (ADHD) is among the most problematic and controversial disorders during childhood and even adulthood period. There are several evidence-based treatment methods for this disorder including: prescribing stimulant and non-stimulant medications to these children, behavior modification methods applied for attention deficit hyperactivity disorder children by their parents, teachers or health care professionals and rehabilitation-based treatments that are emerging in the current years. Rehabilitation involves presentation of repeated progressive exercises of a specific cognitive or motor task over a relatively long period of time to improve participants' performance on trained tasks and as well as to transfer performance improvements to those tasks that had not been specifically trained in the training process. The current research aimed to compare the effectiveness of rehabilitation and drug therapy approaches in improving clinical symptoms and academic performance in children with attention deficit hyperactivity disorder. Methods: The research design was semi-experimental with post-test and follow-up assessments, comparing three groups in a single-blind design. 48 ADHD children were selected using criterion sampling method. These children were first diagnosed with ADHD through performing several semi-structured interviews with their parents, teachers and the children themselves and then the diagnosed and selected children with ADHD matched for IQ and ADHD severity, and randomly assigned to either rehabilitation (n=16) , drug therapy (n=16) and control (n=16) groups. To match the children in IQ, all these participants were tested by a three-subscale short-form of the WISC-R tests. All these children also participated in Dictation and Spelling examinations, Wechsler's arithmetic subtest and their parents rated them on child syndrome inventory-4 (CSI-4) and Swanson, Nolan, and Pelham's parent rating scale (SNAP-IV). The data was analyzed using MANOVA, post hoc univariate ANOVAs and paired t-tests with Bonferroni corrections. Results: Compared to drug therapy participants, the rehabilitation participants showed significant improvements in predominantly inattentive subtype (p=0.012) and sub scales of dictation and spelling (p<0.01). Although, participants in rehabilitation group outperformed participants in control groupin arithmetic task (p=0.034), predominantly hyperactive-impulsive subscale (p=0.042), and combined ADHD subscale from SNAP-IV (p=0.023), the differences between rehabilitation participants and drug therapy participants were not statistically significant. In follow-up assessment, however, drug therapy improvements returned to the baseline level, while participants in rehabilitation group did not showed such decreased improvements. Conclusion: Altogether, the results indicated that rehabilitation is an effective treatment in reducing clinical symptoms and improving school functioning of children with attention deficit hyperactivity disorder. The rehabilitation-related improvement in discovering the symptoms and performance functioning of children with attention deficit hyperactivity disorder tends to last longer than improvements related to drug therapy. Hence rehabilitation can be seen as a complementary technique to drug therapy in the treatment of attention deficit hyperactivity disorder. The limitations of the present study should be taken into account when interpreting these results. This study failed to use more objective measures in the assessment of attention deficit hyperactivity disorder symptoms and children's task performance such as behavioral observations and Electro-Encephalography measures. More research remains to be carried out to verify hypotheses and findings of this research.